vhost-net: move stubs to a separate file

There is no reason for CONFIG_VHOST_NET to be specific to a single target;
it is a host feature that can be add to all targets, as long as they support
the virtio-net device.  Currently CONFIG_VHOST_NET depends on CONFIG_KVM,
but ioeventfd support is present in the core memory API and works with
other accelerators as well.

As a first step, move the vhost-net stubs to a separate file.  Later, they
will become conditional on CONFIG_VIRTIO_NET, which is not available in .c
files.

Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <1543851204-41186-2-git-send-email-pbonzini@redhat.com>
Message-Id: <1550165756-21617-2-git-send-email-pbonzini@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

hw/net/Makefile.objs

@@ -37,7 +37,9 @@ obj-$(CONFIG_PSERIES) += spapr_llan.o
 obj-$(CONFIG_XILINX_ETHLITE) += xilinx_ethlite.o
 
 obj-$(CONFIG_VIRTIO_NET) += virtio-net.o
-obj-y += vhost_net.o
+obj-$(CONFIG_VHOST_NET) += vhost_net.o
+common-obj-$(call lnot,$(CONFIG_VHOST_NET)) += vhost_net-stub.o
+common-obj-$(CONFIG_ALL) += vhost_net-stub.o
 
 obj-$(CONFIG_ETSEC) += fsl_etsec/etsec.o fsl_etsec/registers.o \
 			fsl_etsec/rings.o fsl_etsec/miim.o

hw/net/vhost_net-stub.c

+/*
+ * vhost-net support
+ *
+ * Copyright Red Hat, Inc. 2010
+ *
+ * Authors:
+ *  Michael S. Tsirkin <mst@redhat.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ */
+
+#include "qemu/osdep.h"
+#include "net/net.h"
+#include "net/tap.h"
+#include "net/vhost-user.h"
+
+#include "hw/virtio/virtio-net.h"
+#include "net/vhost_net.h"
+#include "qemu/error-report.h"
+
+
+uint64_t vhost_net_get_max_queues(VHostNetState *net)
+{
+    return 1;
+}
+
+struct vhost_net *vhost_net_init(VhostNetOptions *options)
+{
+    error_report("vhost-net support is not compiled in");
+    return NULL;
+}
+
+int vhost_net_start(VirtIODevice *dev,
+                    NetClientState *ncs,
+                    int total_queues)
+{
+    return -ENOSYS;
+}
+void vhost_net_stop(VirtIODevice *dev,
+                    NetClientState *ncs,
+                    int total_queues)
+{
+}
+
+void vhost_net_cleanup(struct vhost_net *net)
+{
+}
+
+uint64_t vhost_net_get_features(struct vhost_net *net, uint64_t features)
+{
+    return features;
+}
+
+void vhost_net_ack_features(struct vhost_net *net, uint64_t features)
+{
+}
+
+uint64_t vhost_net_get_acked_features(VHostNetState *net)
+{
+    return 0;
+}
+
+bool vhost_net_virtqueue_pending(VHostNetState *net, int idx)
+{
+    return false;
+}
+
+void vhost_net_virtqueue_mask(VHostNetState *net, VirtIODevice *dev,
+                              int idx, bool mask)
+{
+}
+
+int vhost_net_notify_migration_done(struct vhost_net *net, char* mac_addr)
+{
+    return -1;
+}
+
+VHostNetState *get_vhost_net(NetClientState *nc)
+{
+    return 0;
+}
+
+int vhost_set_vring_enable(NetClientState *nc, int enable)
+{
+    return 0;
+}
+
+int vhost_net_set_mtu(struct vhost_net *net, uint16_t mtu)
+{
+    return 0;
+}

hw/net/vhost_net.c

@@ -23,7 +23,6 @@
 #include "qemu/error-report.h"
 
 
-#ifdef CONFIG_VHOST_NET
 #include <linux/vhost.h>
 #include <sys/socket.h>
 #include <linux/kvm.h>
@@ -449,76 +448,3 @@ int vhost_net_set_mtu(struct vhost_net *net, uint16_t mtu)
 
     return vhost_ops->vhost_net_set_mtu(&net->dev, mtu);
 }
-
-#else
-uint64_t vhost_net_get_max_queues(VHostNetState *net)
-{
-    return 1;
-}
-
-struct vhost_net *vhost_net_init(VhostNetOptions *options)
-{
-    error_report("vhost-net support is not compiled in");
-    return NULL;
-}
-
-int vhost_net_start(VirtIODevice *dev,
-                    NetClientState *ncs,
-                    int total_queues)
-{
-    return -ENOSYS;
-}
-void vhost_net_stop(VirtIODevice *dev,
-                    NetClientState *ncs,
-                    int total_queues)
-{
-}
-
-void vhost_net_cleanup(struct vhost_net *net)
-{
-}
-
-uint64_t vhost_net_get_features(struct vhost_net *net, uint64_t features)
-{
-    return features;
-}
-
-void vhost_net_ack_features(struct vhost_net *net, uint64_t features)
-{
-}
-
-uint64_t vhost_net_get_acked_features(VHostNetState *net)
-{
-    return 0;
-}
-
-bool vhost_net_virtqueue_pending(VHostNetState *net, int idx)
-{
-    return false;
-}
-
-void vhost_net_virtqueue_mask(VHostNetState *net, VirtIODevice *dev,
-                              int idx, bool mask)
-{
-}
-
-int vhost_net_notify_migration_done(struct vhost_net *net, char* mac_addr)
-{
-    return -1;
-}
-
-VHostNetState *get_vhost_net(NetClientState *nc)
-{
-    return 0;
-}
-
-int vhost_set_vring_enable(NetClientState *nc, int enable)
-{
-    return 0;
-}
-
-int vhost_net_set_mtu(struct vhost_net *net, uint16_t mtu)
-{
-    return 0;
-}
-#endif